Improvement iw dental forceps



N. A. DU R HAM.

Dental-Forceps;

Patented July 20,1875.

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NEPTHALI A. DURHAM, OF HARTFORD, CONNECTICUT.

IMPROVEMENT IN Specification forming part of Letters Patent No.

DENTAL FORCEPS.

165,808, dated July 20, 1875; application filed May 21, 1875.

To all whom it may concern Be it known that I, NEPTHALI A. DURHAM, ofHartford, in the State of Connecticut, have invented an Improvement inDental Forceps, of which the following is a specification This inventionrelates to that class of dental forceps provided with removable beaks,the shanks whereof are fitted and enter with a lateral movement intocurved sockets in the forceps-handles, so that pressure of said beaksupon any interposed object will tend to drive said shanks home into saidsockets.

Heretofore said sockets and corresponding shanks have been made not onlycurved, but with angular cross-sections, very difficult of accurateconstruction, and not affording a steady attachment for the beak untilentirely home upon its seat.

My invention consists, first, in making the socket straight, and withcircular cross-section, and entering the handle in a lateral directionfrom its inner side. Second, in making the said socket parallel wit-hthe end surface of the handle, against which the shoulders of the beakrest. Third, in the pin-sprin g or frictiondetent located in the middleof said socket, and in an axial orifice in the shank of the beak.

That others may more fully understand the detail of construction of myinvention, I will more particularly describe it, having reference to theaccompanying drawings, wherein- Figure 1 is a perspective view of myforcep, with one of the beaks detached. Fig. 2 represents in perspectivethe set of left-hand beaks. Fig. 3 represents in perspective the set ofright-hand beaks.. Fig. 4 is a longitudinal section of the socket. Fig.5 is a plan of the same.

i The handles A A are jointed together in the usual way at a. Just infront of thejoint a the handles terminate with a plan, shoulder, orsurface, I), slightly inclined inward to the axis of the handle. Atabout one-quarter of an inch below the shoulder 12, on the inner surfaceof the handle A, I make the socket C circular in cross-section, becauseof the mechanical ease of production. The socket C penetrates the handleexactly parallel with the surface b, and extends through aboutthree-fourths the width of the handle, measur= I ing from inner to outersurface. A groove, d, is formed, connecting the socket C with thesurface I) said groove is less in width than the diameter of the socket,and extends to the same depth. At the outer end, the groove d isextended over to the outer surface of the handle, as shown at c. with ashank, f, exactly corresponding to and fitting the socket c and grooved, with an offset, g, fitting the groove-offset at c.

It will readily be perceived that when the shank f is inserted in itssocket it will be held there positively, as against the strains incidentto use, without the employment of any latching or movable holdingdevices what ever.

Frequent insertion and removal of the shank from its socket will cause aslight wearin g of the surface and a consequent looseness. To correctthe objectionable result of this slight wearing of the surface, afriction-sprin g is inserted in the socket, which will always press theshank forward and bring into contact the resisting surfaces, so that,however loosely the shank may fit its socket, the beak will always be inoperative position and will not yield when brought into use. Africtionspring for this purpose may be inserted in a variety of ways,which will readily occur to any skillful mechanic 5 but I prefer toinsert it as shown in Fig. 5 of the drawing. The enlarged portion of theshank f is perforated,

serted axially in the socket c. The opposite sides of the screw are cutaway so as to form end, which, entering the perforation h as the shankis inserted, presses against the forward side of said perforation andnear .the inner side of the beak, so as to constantly press theresisting surfaces of the shank and socket together and keep them alwaysin operative position.

By this means the shank is held securely against all pulling strains;but twisting or side strains are also effectually resisted by the web ofthe shank, which extends across the entire width of the handle at e 9.

Having described my invention, what I claim as new is- 1. Aforcep-handle, provided with a straight The beak F is made as at h,lengthwise, and a steel screw, 2', is ina spring, leaving a knob or bossat its outer socket, having a circular cross-section, enter- 3. Thepin-spring i, located in the middle of ing' laterally from the innerside of said handle, the socket 0, combined with the shank f, 0011- andprovided with a slot, d, combined with a strueted with the orifice h,for the purpose set beak constructed with a corresponding shank, forth.as set forth.

2. A forcep-handle, A, constructed with the NEPTHALI A. DURHAM. planeend I) and the socket 0 parallel with said surface I), combined with thebeak F, In the presence of provided with the shank f fitted to saidsocket DWIGHT W. CLARK, and groove, as set forth. WILLIAM W. CROSBY.

